Determination of 10 Volatile Organic Compounds in Oil-Based Metal Working Fluid by Headspace-Gas Chromatography

(5.00±0.01) g of the oil-based metal-working fluid sample were taken and placed into the headspace flask. After capping of the headspace flask, the headspace processing was carried out according to the optimized conditions of equilibrium temperature (145℃) and equilibrium time (30 min), with volume and temperature of the quantitative circle of 1 mL and 155℃, and time of sample introduction of 0.5 min. Gas chromatography separation was performed on HP-5 capillary chromatographic column (30 m×320 μm, 0.5 μm) and under temperature elevation program in the temperature interval between 35℃ to 160℃. Nitrogen was used as carrying gas. FID was used for measuring the peak areas of the 10 analytes of VOCs in the sample, namely dichloromethane, n-hexane, benzene, toluene, n-octane, ethylbenzene, p-dimethylbenzene, o-dimethylbenzene, nonane and undecane. The v-slov base oil was selected as matrix in headspace operation and in preparation of standard curves by addition of mixed standard solution of the 10 VOCs. Linear relationships between values of peak areas and the mass fraction of the respective analytes were found in definite ranges, having linear correlation coefficients greater than 0.999. Values of lower limits (10S/N) of determination of the 10 VOCs were found in the range of 0.40-10 mg·kg^-1. Test for recovery was made by standard addition using a known sample as matrix. Results of recovery were found ranged from 88.0% to 115%. Values of RSDs (n=6) were found in the range of 1.0%-5.6%.